O objetivo principal deste estudo foi investigar o efeito da posição de coordenação, proposta no método da coordenação motora de Piret e Béziers (1992), na resposta de torque em preensão digital. Dezesseis jovens adultos (24,7 ± 2,2 anos de idade) foram solicitados a realizar duas tarefas distintas: produção de torque máximo em preensão digital e controle de torque em preensão digital constante e contínuo. Ambas as tarefas foram avaliadas em quatro diferentes posições do cotovelo (posição livre, em extensão, 45º de flexão e 90º de flexão) e três níveis relativos distintos de torque máximo (20%, 40% e 60%). Pique do torque máximo, variabilidade, irregularidade e precisão da resposta motora foram utilizados como variáveis dependentes. Os resultados não revelaram efeito da posição do cotovelo na produção de torque em preensão digital máximo e nem na resposta de controle de torque em preensão digital. Todavia, a resposta de controle de torque mostrou-se mais variável, mais irregular e menos precisa com o incremento dos níveis relativos de torque máximo. Tais achados não oferecem suporte à premissa do método da coordenação motora, o qual preconiza a existência de uma posição articular ótima do membro superior para a coordenação e controle motor. Além disso, os resultados permitem a constatação de que maiores níveis de torque demandam ajustes neuromotores mais complexos no sistema sensório-motor, todavia a posição do cotovelo parece não caracterizar-se como uma restrição determinante da tarefa de torque em preensão digital. / The main aim of this study was to investigate the effect of the coordination position, proposed by the coordination method (Piret & Bézier, 1992), on the thumb-index torque production. Sixteen young adults (24,7 ± 2,2 years old) were asked to perform two different tasks: Maximum thumb-index torque production and constant thumb-index torque. Both tasks were evaluated in four different elbow positions (free position, extension, 45º of flexion and 90º of flexion) and three relative levels of maximum thumb-index torque production (20%, 40% & 60%). Maximum peak torque, variability, irregularity and accuracy were used as dependent variables. The results showed neither effects of the elbow position on the maximum thumb-index torque production nor in the constant thumb-index torque task. However, the constant thumb-index torque responses were more variable, more irregular and less accurate with increased relative levels of the thumb-index torque production. These findings do not support the coordination method premise that we have an optimum upper-limb position which provides a better coordination and motor control. Furthermore, the results allow the interpretation that larger level of the thumb-index torque production demands more complex neuromuscular adjustments of the motor-sensory system; however, the elbow position does not appear to be a determinant constraint during a thumb-index torque task.

Assimetrias de desempenho, frequentemente, são relacionadas ao controle e desenvolvimento motor da extremidade superior. Por outro lado, a extremidade inferior do corpo humano está muito mais envolvida em ações bilaterais, como aquelas relacionadas à locomoção. Ainda assim, diferenças no desempenho dos membros inferiores foram descritos na literatura, como, por exemplo, em relação à força durante tarefas de andar, correr e pedalar. As razões para essas diferenças - uma vez que ambos os membros inferiores, teoricamente, tem a mesma possibilidade de movimento e a preferência lateral pode mudar de acordo com a tarefa - tem intrigado cientistas. Em estudos prévios apresentados na literatura, notamos que assimetrias na força produzida ocorrem durante a pedalada, apresentando relação, por exemplo, com a intensidade do exercício. Também sugere-se que a experiência com a tarefa influencie assimetrias. Entre os motivos para estudar esses mecanismos de assimetria está o risco aumentado de lesão inerente a assimetrias cinéticas, como constatado na corrida, assim como a importância de empregar estratégias unilaterais de treinamento e/ou reabilitação. A ativação muscular foi sugerida como sendo um fator determinante de assimetrias. A ativação muscular nos membros inferiores poderia diferir entre os membros, e tal como ocorre para a extremidade superior, levar a vantagem em favor da perna preferida. No entanto, essa hipótese não havia sido testada, considerando exercícios em diferentes configurações e sujeitos com diferentes níveis de experiência. Assim, buscamos investigar as diferenças entre o membro inferior preferido e não-preferido durante a pedalada, em testes bilaterais e unilaterais, considerando: (1) o consumo de oxigênio, (2) a eficiência muscular, (3) a magnitude da ativação muscular, (4) a variabilidade na ativação muscular, e (5) a comunicação entre os membros durante ações isoladas de um dos membros inferiores. Protocolos de ciclismo (a) incremental máximo, (b) submáximo de carga constante para pedalada bilateral, e (c) submáximo de carga constante para pedalada unilateral, com o membro inferior preferido e não-preferido, foram realizados por ciclistas e não-ciclistas. As análises estatísticas sugeriram que durante a pedalada bilateral, assimetrias de força previamente descritas não parecem estar relacionadas com diferenças na magnitude de ativação muscular (biceps femoris, gastrocnemius medialis e vastus lateralis) entre o membro inferior preferido e nãopreferido. No entanto, a variabilidade da ativação foi influenciada pela preferência em não-ciclistas. No exercício unilateral, a preferência lateral não influenciou o consumo de oxigênio e a eficiência muscular. A magnitude da ativação muscular e a sua variabilidade também não diferiram estatisticamente entre as pernas durante os protocolos unilaterais, o que não ajuda a explicar assimetrias de força dependentes em aspectos neurais. Os resultados de comunicação entre membros sugerem efeitos da preferência lateral para ciclistas na perna preferida, o que poderia influenciar a transferência interlateral de aprendizagem em sujeitos treinados. Dessa forma, a preferência lateral parece não influenciar a magnitude da ativação muscular e eficiência muscular, no entanto, ela pode apresentar diferentes efeitos frente à variabilidade da ativação muscular e da comunicação entre os membros em função da experiência com ciclismo. Assimetrias encontradas no ciclismo parecem mais frequentes para a força e podem ser relacionadas à configuração da atividade e ao efeito do ambiente de prática, sem apresentar correlatos com a ativação muscular. / Performance asymmetries are frequently addressed by studies on motor control. Research projects adopt protocols which will assess unimanual and bimanual action in order to determine lateralization and transfer of learning processes, as well as to monitor the development of learning. On the other hand, the lower limbs of the human body are more related to bilateral actions, such as those required for locomotion. Nevertheless, differences in the performance between lower limbs have been reported in previous investigations for force, during walking, running and cycling. The factors which determine these differences - once both lower limbs in theory have the same possibility to be recruited and the leg preference can switch according to the tasks requirements - have been discussed in the literature. Previous studies from the literature reported force asymmetries during pedaling, which appeared dependent on exercise intensity and experience. Among the motivations to study mechanisms of asymmetry is the increased risk of injury associated with kinetic asymmetries, as previously described for runners, as well the development of unilateral strategies of training and rehabilitation. Muscle activation was suggested as a factor determinant of limb asymmetries. The muscle activation could differ between lower limbs as observed for upper extremity, and lead to advantages in favor of preferred limb during dynamic actions. Although proposed in the literature, this hypothesis was not tested using different configurations of exercise and subjects with different levels of experience with pedaling. Therefore, we investigated differences between preferred and non-preferred limbs during bilateral and unilateral pedaling. Parameters measured included (1) oxygen uptake, (2) muscle efficiency, (3) magnitude of muscle activation (4) variability of muscle activation, and (5) interlimb excitation during isolated actions of one limb. Cycling protocols consisted of (a) incremental maximal cycling test, (b) bilateral pedaling at submaximal intensity, and (c) unilateral pedaling at submaximal intensity, with preferred and non-preferred limbs. Tests were performed by cyclists and non-cyclists. The statistical analysis suggested that during bilateral pedaling, force asymmetries described in the literature appeared not related to differences in magnitude of muscle activation (biceps femoris, gastrocnemius medial head, and vastus lateralis) between preferred and non-preferred lower limbs. Despite of this, variability of muscle activation was influenced by leg preference in noncyclists. During unilateral pedaling, leg preference did not statistically influence oxygen uptake and muscle efficiency. Magnitude of muscle activation and its variability did not differ statistically between legs. This finding does not support force asymmetry as dependent on neural factors related to the magnitude of muscle activation. The result of interlimb excitation suggests the effects of lateral preference for the preferred leg of cyclists, which could influence the interlimb transfer of learning in trained subjects. In summary, lateral preference appeared not to influence magnitude of lower limbs muscle activation and muscle efficiency, but can present different effects on variability of muscle activation and interlimb communication according to cycling experience. Asymmetries found during cycling appear more frequent for force and can be dependent on the exercise configuration and environment, without correlation with the muscle activation.

xiii, 79 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Traumatic brain injury has reached epidemic levels, and yet there are still large questions that need to be addressed regarding the underlying pathology and the related behavioral deficits. Adequately measuring the neurological sequelae associated with TBI in vivo requires the use of sophisticated imaging procedures, while quantifying behavioral deficits requires precise, sensitive testing procedures. The current analysis examined three potential biomarkers of TBI using MRI technology, as well as examining both fine motor and psychological function on a cohort of TBI participants at least 12 months post-injury. Ten participants with a history of traumatic brain injury and ten matched controls were recruited for the present analysis. All participants completed a series of four MRI scans, as well as a simple motor task and a cognitive test battery. Between group analysis revealed that the two groups could be differentiated based on two MRI measures (BOLD and FA), and on three behavioral measures (Fitts motor task, self-reported symptoms, and impulse control). A within group correlation analysis of the TBI participants did not reveal any significant relationship between the MRI data and behavioral deficits. A group-wide regression analysis, however, revealed that MRI markers of cortical damage significantly predicted deterioration in the Fitts motor task performance. The results of the current study suggest that the long-term effects of TBI are not confined to executive function, and that one's performance of a fine motor task has diagnostic potential. / Adviser: Paul van Donkelaar

O objetivo principal deste estudo foi investigar o efeito da posição de coordenação, proposta no método da coordenação motora de Piret e Béziers (1992), na resposta de torque em preensão digital. Dezesseis jovens adultos (24,7 ± 2,2 anos de idade) foram solicitados a realizar duas tarefas distintas: produção de torque máximo em preensão digital e controle de torque em preensão digital constante e contínuo. Ambas as tarefas foram avaliadas em quatro diferentes posições do cotovelo (posição livre, em extensão, 45º de flexão e 90º de flexão) e três níveis relativos distintos de torque máximo (20%, 40% e 60%). Pique do torque máximo, variabilidade, irregularidade e precisão da resposta motora foram utilizados como variáveis dependentes. Os resultados não revelaram efeito da posição do cotovelo na produção de torque em preensão digital máximo e nem na resposta de controle de torque em preensão digital. Todavia, a resposta de controle de torque mostrou-se mais variável, mais irregular e menos precisa com o incremento dos níveis relativos de torque máximo. Tais achados não oferecem suporte à premissa do método da coordenação motora, o qual preconiza a existência de uma posição articular ótima do membro superior para a coordenação e controle motor. Além disso, os resultados permitem a constatação de que maiores níveis de torque demandam ajustes neuromotores mais complexos no sistema sensório-motor, todavia a posição do cotovelo parece não caracterizar-se como uma restrição determinante da tarefa de torque em preensão digital. / The main aim of this study was to investigate the effect of the coordination position, proposed by the coordination method (Piret & Bézier, 1992), on the thumb-index torque production. Sixteen young adults (24,7 ± 2,2 years old) were asked to perform two different tasks: Maximum thumb-index torque production and constant thumb-index torque. Both tasks were evaluated in four different elbow positions (free position, extension, 45º of flexion and 90º of flexion) and three relative levels of maximum thumb-index torque production (20%, 40% & 60%). Maximum peak torque, variability, irregularity and accuracy were used as dependent variables. The results showed neither effects of the elbow position on the maximum thumb-index torque production nor in the constant thumb-index torque task. However, the constant thumb-index torque responses were more variable, more irregular and less accurate with increased relative levels of the thumb-index torque production. These findings do not support the coordination method premise that we have an optimum upper-limb position which provides a better coordination and motor control. Furthermore, the results allow the interpretation that larger level of the thumb-index torque production demands more complex neuromuscular adjustments of the motor-sensory system; however, the elbow position does not appear to be a determinant constraint during a thumb-index torque task.

Assimetrias de desempenho, frequentemente, são relacionadas ao controle e desenvolvimento motor da extremidade superior. Por outro lado, a extremidade inferior do corpo humano está muito mais envolvida em ações bilaterais, como aquelas relacionadas à locomoção. Ainda assim, diferenças no desempenho dos membros inferiores foram descritos na literatura, como, por exemplo, em relação à força durante tarefas de andar, correr e pedalar. As razões para essas diferenças - uma vez que ambos os membros inferiores, teoricamente, tem a mesma possibilidade de movimento e a preferência lateral pode mudar de acordo com a tarefa - tem intrigado cientistas. Em estudos prévios apresentados na literatura, notamos que assimetrias na força produzida ocorrem durante a pedalada, apresentando relação, por exemplo, com a intensidade do exercício. Também sugere-se que a experiência com a tarefa influencie assimetrias. Entre os motivos para estudar esses mecanismos de assimetria está o risco aumentado de lesão inerente a assimetrias cinéticas, como constatado na corrida, assim como a importância de empregar estratégias unilaterais de treinamento e/ou reabilitação. A ativação muscular foi sugerida como sendo um fator determinante de assimetrias. A ativação muscular nos membros inferiores poderia diferir entre os membros, e tal como ocorre para a extremidade superior, levar a vantagem em favor da perna preferida. No entanto, essa hipótese não havia sido testada, considerando exercícios em diferentes configurações e sujeitos com diferentes níveis de experiência. Assim, buscamos investigar as diferenças entre o membro inferior preferido e não-preferido durante a pedalada, em testes bilaterais e unilaterais, considerando: (1) o consumo de oxigênio, (2) a eficiência muscular, (3) a magnitude da ativação muscular, (4) a variabilidade na ativação muscular, e (5) a comunicação entre os membros durante ações isoladas de um dos membros inferiores. Protocolos de ciclismo (a) incremental máximo, (b) submáximo de carga constante para pedalada bilateral, e (c) submáximo de carga constante para pedalada unilateral, com o membro inferior preferido e não-preferido, foram realizados por ciclistas e não-ciclistas. As análises estatísticas sugeriram que durante a pedalada bilateral, assimetrias de força previamente descritas não parecem estar relacionadas com diferenças na magnitude de ativação muscular (biceps femoris, gastrocnemius medialis e vastus lateralis) entre o membro inferior preferido e nãopreferido. No entanto, a variabilidade da ativação foi influenciada pela preferência em não-ciclistas. No exercício unilateral, a preferência lateral não influenciou o consumo de oxigênio e a eficiência muscular. A magnitude da ativação muscular e a sua variabilidade também não diferiram estatisticamente entre as pernas durante os protocolos unilaterais, o que não ajuda a explicar assimetrias de força dependentes em aspectos neurais. Os resultados de comunicação entre membros sugerem efeitos da preferência lateral para ciclistas na perna preferida, o que poderia influenciar a transferência interlateral de aprendizagem em sujeitos treinados. Dessa forma, a preferência lateral parece não influenciar a magnitude da ativação muscular e eficiência muscular, no entanto, ela pode apresentar diferentes efeitos frente à variabilidade da ativação muscular e da comunicação entre os membros em função da experiência com ciclismo. Assimetrias encontradas no ciclismo parecem mais frequentes para a força e podem ser relacionadas à configuração da atividade e ao efeito do ambiente de prática, sem apresentar correlatos com a ativação muscular. / Performance asymmetries are frequently addressed by studies on motor control. Research projects adopt protocols which will assess unimanual and bimanual action in order to determine lateralization and transfer of learning processes, as well as to monitor the development of learning. On the other hand, the lower limbs of the human body are more related to bilateral actions, such as those required for locomotion. Nevertheless, differences in the performance between lower limbs have been reported in previous investigations for force, during walking, running and cycling. The factors which determine these differences - once both lower limbs in theory have the same possibility to be recruited and the leg preference can switch according to the tasks requirements - have been discussed in the literature. Previous studies from the literature reported force asymmetries during pedaling, which appeared dependent on exercise intensity and experience. Among the motivations to study mechanisms of asymmetry is the increased risk of injury associated with kinetic asymmetries, as previously described for runners, as well the development of unilateral strategies of training and rehabilitation. Muscle activation was suggested as a factor determinant of limb asymmetries. The muscle activation could differ between lower limbs as observed for upper extremity, and lead to advantages in favor of preferred limb during dynamic actions. Although proposed in the literature, this hypothesis was not tested using different configurations of exercise and subjects with different levels of experience with pedaling. Therefore, we investigated differences between preferred and non-preferred limbs during bilateral and unilateral pedaling. Parameters measured included (1) oxygen uptake, (2) muscle efficiency, (3) magnitude of muscle activation (4) variability of muscle activation, and (5) interlimb excitation during isolated actions of one limb. Cycling protocols consisted of (a) incremental maximal cycling test, (b) bilateral pedaling at submaximal intensity, and (c) unilateral pedaling at submaximal intensity, with preferred and non-preferred limbs. Tests were performed by cyclists and non-cyclists. The statistical analysis suggested that during bilateral pedaling, force asymmetries described in the literature appeared not related to differences in magnitude of muscle activation (biceps femoris, gastrocnemius medial head, and vastus lateralis) between preferred and non-preferred lower limbs. Despite of this, variability of muscle activation was influenced by leg preference in noncyclists. During unilateral pedaling, leg preference did not statistically influence oxygen uptake and muscle efficiency. Magnitude of muscle activation and its variability did not differ statistically between legs. This finding does not support force asymmetry as dependent on neural factors related to the magnitude of muscle activation. The result of interlimb excitation suggests the effects of lateral preference for the preferred leg of cyclists, which could influence the interlimb transfer of learning in trained subjects. In summary, lateral preference appeared not to influence magnitude of lower limbs muscle activation and muscle efficiency, but can present different effects on variability of muscle activation and interlimb communication according to cycling experience. Asymmetries found during cycling appear more frequent for force and can be dependent on the exercise configuration and environment, without correlation with the muscle activation.

abstract: Locomotion in natural environments requires coordinated movements from multiple body parts, and precise adaptations when changes in the environment occur. The contributions of the neurons of the motor cortex underlying these behaviors are poorly understood, and especially little is known about how such contributions may differ based on the anatomical and physiological characteristics of neurons. To elucidate the contributions of motor cortical subpopulations to movements, the activity of motor cortical neurons, muscle activity, and kinematics were studied in the cat during a variety of locomotion tasks requiring accurate foot placement, including some tasks involving both expected and unexpected perturbations of the movement environment. The roles of neurons with two types of neuronal characteristics were studied: the existence of somatosensory receptive fields located at the shoulder, elbow, or wrist of the contralateral forelimb; and the existence projections through the pyramidal tract, including fast- and slow-conducting subtypes. Distinct neuronal adaptations between simple and complex locomotion tasks were observed for neurons with different receptive field properties and fast- and slow-conducting pyramidal tract neurons. Feedforward and feedback-driven kinematic control strategies were observed for adaptations to expected and unexpected perturbations, respectively, during complex locomotion tasks. These kinematic differences were reflected in the response characteristics of motor cortical neurons receptive to somatosensory information from different parts of the forelimb, elucidating roles for the various neuronal populations in accommodating disturbances in the environment during behaviors. The results show that anatomical and physiological characteristics of motor cortical neurons are important for determining if and how neurons are involved in precise control of locomotion during natural behaviors. / Dissertation/Thesis / Doctoral Dissertation Neuroscience 2015

abstract: The human hand is a complex biological system. Humans have evolved a unique ability to use the hand for a wide range of tasks, including activities of daily living such as successfully grasping and manipulating objects, i.e., lifting a cup of coffee without spilling. Despite the ubiquitous nature of hand use in everyday activities involving object manipulations, there is currently an incomplete understanding of the cortical sensorimotor mechanisms underlying this important behavior. One critical aspect of natural object grasping is the coordination of where the fingers make contact with an object and how much force is applied following contact. Such force-to-position modulation is critical for successful manipulation. However, the neural mechanisms underlying these motor processes remain less understood, as previous experiments have utilized protocols with fixed contact points which likely rely on different neural mechanisms from those involved in grasping at unconstrained contacts. To address this gap in the motor neuroscience field, transcranial magnetic stimulation (TMS) and electroencephalography (EEG) were used to investigate the role of primary motor cortex (M1), as well as other important cortical regions in the grasping network, during the planning and execution of object grasping and manipulation. The results of virtual lesions induced by TMS and EEG revealed grasp context-specific cortical mechanisms underlying digit force-to-position coordination, as well as the spatial and temporal dynamics of cortical activity during planning and execution. Together, the present findings provide the foundation for a novel framework accounting for how the central nervous system controls dexterous manipulation. This new knowledge can potentially benefit research in neuroprosthetics and improve the efficacy of neurorehabilitation techniques for patients affected by sensorimotor impairments. / Dissertation/Thesis / Doctoral Dissertation Neuroscience 2017

The aim of this thesis was to investigate and appraise the utility of analogy and explicit instruction for applied sport and physical education settings. The objective for the first study was to explore the acute, short-term impact of analogical and explicit instruction in a dart-throwing task. While previous studies have devoted considerable resources to investigating the effects of verbal instruction on motor learning, this within-subjects study explored the impact of analogical and explicit instruction on motor control. Interestingly, results indicated that analogy and explicit instruction similarly impaired throwing accuracy—in both kinematic and outcome measures—compared to baseline conditions, conflicting with trends observed in the motor learning literature. In the second study, the differential effects of analogy and explicit instructions on early stage motor learning were examined by introducing an explicit light condition—in addition to a traditional explicit condition—that matched the analogy instructions in informational volume. Although analogy learners demonstrated slightly more efficient technique and reported fewer technical rules on average, the differences between groups were not statistically significant. Kinematic analysis, however, did reveal significant differences between conditions in joint variability, which decreased with learning for all groups, but was lowest overall for the analogy learners. For the final study, the thesis investigated the impact of analogy and explicit instruction on adolescent performance (mean age = 12.7 years, SD = 0.4) in a modified high jump task. To date, research in analogy instruction has only included adult participants whose movement tendencies have likely already been shaped by personal or vicarious experiences. Analyses indicated that there were no significant differences between the analogy and explicit participants in technical efficiency or joint variability. The key outcome from this thesis is that there is limited evidence to support the use of analogy instruction over explicit instructional methods in motor learning and motor control situations.

Les modèles biomécaniques éléments finis (EF) sont couramment utilisés dans de nombreux domaines. Ces modèles tendent depuis quelques années à être actifs, capable donc de générer des efforts musculaires et des mouvements. L’étape suivante consiste à rendre ces modèles réactifs, c’est-à-dire capable de réagir à une situation quelconque par des contractions musculaires et des mouvements. C’est dans cet optique que ce projet a été décomposé en 3 étapes. La première consistait à réaliser un modèle biomécanique détaillé capable de contractions musculaires et de mouvements. La seconde étape consistait à introduire des réflexes. Pour cela des modèles de capteurs sensoriels (fuseaux neuromusculaires et organes tendineux de golgi) et les réflexes associés (réflexes myotatiques et myotatiques inverses) ont ensuite été introduits au sein même du modèle. Le modèle ainsi obtenu a pu ensuite être validé grâce à une campagne expérimentale de quantification du réflexe d’étirement du tendon du biceps brachial. La dernière étape consistait à introduire des réactions de niveau supérieur, c’est-à-dire des mouvements volontaires. Pour cela une méthode de contrôle basée sur de l’apprentissage et l’optimisation a permis de générer ces mouvements et de les contrôler.En conclusion, l’introduction de boucles sensorielles et motrices de différents niveaux dans un modèle EF permet de rendre ce dernier réactif à son environnement. En effet, le modèle est ainsi capable de générer un mouvement selon des objectifs et des contraintes. Il est également capable d’adapter la contraction musculaire en fonction des évènements intervenant lors de la réalisation du mouvement. / Biomechanical finite elements (FE) models are commonly used in the field of road safety, sport and medicine. These models tended in recent years to be active, i.e. able to generate muscular efforts or movements. The next step is to make these models reactive, i.e. able to react to a situation with muscle contractions and movement. It is in this context that this project was broken down into 3 steps. The first step was to create a detailed biomechanical model capable of movements and muscle contractions. The second step was to introduce reflexes. For this, physiological sensors models (neuromuscular spindles and golgi tendon organs) and the associated reflexes associated (myotatic and inverse myotatic reflexes) were then integrated into the model. The model thus obtained could then be validated thanks to an experimental campaign of characterization of the deep tendon reflex of the biceps brachial. The last step was to introduce higher-level reactions, i.e. voluntary movements. For this purpose, a control method based on learning and optimization has made it possible to generate and control these movements.In conclusion, the introduction of sensory and motor loops of different into an FE model makes the latter reactive to its environment. Indeed, the model is thus able to generate a movement according to objectives and constraints. He is also able to adapt the muscular contraction according to the events intervening during the realization of the movement.

Orientador: Lilian Teresa Bucken Gobbi / Banca: Sérgio Tosi Rodrigues / Banca: Luis Augusto Teixeira / Resumo: Considerando que indivíduo e ambiente encontram-se dinamicamente relacionados e que o indivíduo encontra no ambiente situações também em movimento, o presente estudo propôs-se a analisar as estratégias locomotoras da ultrapassagem de obstáculo que se movimenta em diferentes velocidades. Participaram 10 adultos jovens, universitários. Com marcadores passivos fixados em referências anatômicas de interesse, cada participante percorreu andando uma passarela de 6 m de comprimento delimitada por um corredor de 0,50 m de largura e ultrapassou o obstáculo que cruzou perpendicularmente sua trajetória em três condições de velocidade. Os resultados revelaram que a velocidade do obstáculo desencadeou ajustes espaciais e temporais nos passos anteriores ao obstáculo. Na ultrapassagem, os resultados evidenciaram que, na velocidade baixa, os participantes aproximaram-se mais do obstáculo antes da ultrapassagem, aumentaram a margem de segurança sobre o obstáculo e a distância após a ultrapassagem, erraram menos e demoraram mais para ultrapassar o obstáculo. Entretanto, na velocidade alta, os participantes aumentaram ainda mais a margem de segurança sobre o obstáculo e afastaram-se mais após a ultrapassagem. Estes resultados indicam que ocorreram modificações no padrão de aproximação e ultrapassagem do obstáculo de acordo com a velocidade / Abstract: Considering that both individual and environment are dynamically related and that the individual find in the environment situations also in movement, the purpose of the present study was to analyze the locomotor strategies during crossing the obstacle, which moved in different speeds. Ten young adults, undergraduate students participated. Passive markers were attached in anatomical landmarks. Each participant walked on a pathway of 6m long and 0.5m wide and passed over an obstacle that perpendicularly (90º) crossed his/her trajectory under three velocity conditions. The results revealed that the obstacle velocity unchained spatial and temporal adjustments in all steps prior to the obstacle. During the crossing phase, the results revealed that in low speed the participants got closer to the obstacle before crossing, increased the safety margin over the obstacle, increased the foot placement after the obstacle, decreased the errors, and increased the time to pass over the obstacle. However, on the high velocity, the participants increased even more the safety margin over the obstacle and increased foot placement after the obstacle. These results showed that the obstacle velocity modulated the approach and crossing patterns / Mestre